The present invention concerns a fibre optic device for homogenizing a laser beam.
It finds a general application in any technical field using a laser, and notably in laser surface treatment, such as the annealing of amorphous silicon, cleaning, polishing and surface preparation.
In general terms, the energy distribution across the cross section of a laser beam, at least in the lowest type of emission, has a gaussian appearance, which is in any case variable across the cross section of the beam.
However, in order to obtain, for example, an optimum annealing of amorphous silicon, it is necessary to apply a laser beam having a homogeneous and substantially uniform energy distribution.
This homogeneity is particularly required when the sample to be treated by laser is of large size (as described in the French Patent Application entitled "Device and method for laser surface treatment" filed in the name of the Applicant on Aug. 11, 1995 under the number 95 09778, and the disclosure of which is incorporated herein by reference. It is also required when the incident laser beam is a combination of several laser beams coming from a line of laser units arranged in parallel and/or in series (as described in the French Patent Application entitled "Method and device for controlling a laser source with several laser units for optimizing laser surface treatment", filed by the Applicant on Aug. 11, 1995 under the number 95 09780, and the disclosure of which is incorporated herein by reference.
Means are already known for homogenizing a laser beam (JP-A-01 286 478, U.S. Pat. No. 5,253,110, EP-A-0 266 120, DE-A-4 220 705 and EP-A-0 097 250).
However, these means are usually complicated, expensive, difficult to implement and ill-suited to beams of large size and high power.
The present invention affords precisely a solution to this problem.